namespace Delegates;

class Program
{
  public delegate int MathFunction(int a, int b);
  public delegate void PrintFunction(int n);
  static void Main(string[] args)
  {
    int x = 16, y = 2;
    MathFunction mf = MathTool.Sum;
    Console.WriteLine("mf({0}, {1}) = {2}", x, y, mf(x, y));
    mf = MathTool.Diff;
    Console.WriteLine("mf({0}, {1}) = {2}", x, y, mf(x, y));
    PrintFunction pf = MathTool.PrintSquare;
    pf += MathTool.PrintSquareRoot;
    pf(x);
#pragma warning disable CS8601 // Possible null reference assignment.
    pf -= MathTool.PrintSquare;
#pragma warning restore CS8601 // Possible null reference assignment.
    Console.WriteLine();
#pragma warning disable CS8602 // Dereference of a possibly null reference.
    pf(y); //instead of pragma pf?.Invoke(y); can be used  
#pragma warning restore CS8602 // Dereference of a possibly null reference.

    Func<int, int, int> func = MathTool.Sum;
    Console.WriteLine("func({0}, {1}) = {2}", x, y, func(x, y));
    
    Action<int> action = MathTool.PrintSquare;
    action(x);
  }
}